@Alexandre That number was from a news article on Ann Arbor News a couple years ago with the info from the university. If target was 5800, then they have been over the target almost every year.
http://www.michigandaily.com/news/provost-announces-plan-curb-over-enrollment
Those links seem to indicate that Michigan was aiming for classes of 5,800-6,000. There is no doubt that we have been well over the target virtually each year,